Khushi engineering consultancy

Page link

https://www.facebook.com/707891459381047/posts/1322238287946358/?app=fbl

Properties of building stone

Structure
The structure of the stone may be stratified (layered) or unstratified. Structured stones should be easily dressed and suitable for super structure. Unstratified stones are hard and difficult to dress. They are preferred for the foundation works.
Texture
Fine grained stones with homogeneous distribution look attractive and hence they are used for carving. Such stones are usually strong and durable.
Density
Denser stones are stronger. Light weight stones are weak. Hence stones with specific gravity less than 2.4 are considered unsuitable for buildings.
Appearance
A stone with uniform and attractive color is durable, if grains are compact. Marble and granite get very good appearance, when polished. Hence they are used for face works in buildings.
Hardness
It is an important property to be considered when stone is used for flooring and pavement. Coefficient of hardness is to be found by conducting test on standard specimen in Dory’s testing machine. For road works coefficient of hardness should be at least 17. For building works stones with coefficient of hardness less than 14 should not be used.
Percentage Wear
It is measured by attrition test. It is an important property to be considered in selecting aggregate for road works and railway ballast. A good stone should not show wear of more than 2%.
Porosity and Absorption
All stones have pores and hence absorb water. The reaction of water with stone causes disintegration. Absorption test is specified as percentage of water absorbed by the stone when it is immersed under water for 24 hours. For a good stone it should be as small as possible and in no case more than 5.
Weathering
Rain and wind cause loss of good appearance of stones. Hence stones with good weather resistance should be used for face works.
Toughness
The resistance to impact is called toughness. It is determined by impact test. Stones with toughness index more than 19 are preferred for road works. Toughness index 13 to 19 is considered as medium tough and stones with toughness index less than 13 are poor stones.
Resistance to Fire
Sand stones resist fire better. Argillaceous materials, though poor in strength, are good in resisting fire.
Ease in Dressing
Cost of dressing contributes to cost of stone masonry to a great extent. Dressing is easy in stones with lesser strength. Hence an engineer should look into sufficient strength rather than high strength while selecting stones for building works.
Seasoning
The stones obtained from quarry contain moisture in the pores. The strength of the stone improves if this moisture is removed before using the stone. The process of removing moisture from pores is called seasoning. The best way of seasoning is to allow it to the action of nature for 6 to 12 months.

Labels: Property of stone

stone

Stones are naturally occurring rocks of igneous, sedimentary or metamorphic origin. Stone or Rock structures have existed for as long as history can recall. Stone is a natural material of construction and is obtained from Quarry (open part of the natural rock from which useful material is obtains). It has been used for constructing different components of building like walls, roof, lintels etc. Stones, which are used for construction of structures, are known as building stones. Stone or Rock structures have existed for as long as history can recall. It is the longest lasting building material available, and is usually readily available. There are many types of stone throughout the world, all with differing attributes that make them better or worse for particular uses. Stone is a very dense material so it gives a lot of protection too; its main drawback as a material is its weight. Its energy density is also considered a big drawback, as stone is hard to keep warm without using large amounts of heating resources. Different forms of mortar were used to hold the stones together, cement being the most common material of mortar. Stone buildings can be seen in most major cities; some civilizations built entirely with stone such as the Egyptian pyramids.

Labels: Stone

Building material

Building materials are the materials required for the construction different types of building. For example:- cement, aggregate, brick, water , concrete blocks, plastics, paints, admixture etc. It is any material which is used for construction purposes Many naturally occurring substances, such as clay, rocks, sand, and wood, even twigs and leaves, have been used to construct buildings. Apart from naturally occurring materials, many man-made products are in use, some more and some less synthetic. The manufacturing of building materials is an established industry in many countries and the use of these materials is typically segmented into specific specialty trades, such as carpentry, insulation, plumbing, and roofing work.

Labels: Building material

Construction materials

1.1 Introduction to Construction Materials
Construction materials are the materials required for the different types of construction works. For example:- cement, aggregate, brick, water , concrete blocks, plastics, paints, admixture, bitumen , mud etc. An understanding of the basic properties of major construction materials is fundamental to becoming an effective architect or engineer. It introduces the properties, applications and design considerations of common construction materials.
1.2 Building material:-
Building materials are the materials required for the construction different types of building. For example:- cement, aggregate, brick, water , concrete blocks, plastics, paints, admixture etc. It is any material which is used for construction purposes Many naturally occurring substances, such as clay, rocks, sand, and wood, even twigs and leaves, have been used to construct buildings. Apart from naturally occurring materials, many man-made products are in use, some more and some less synthetic. The manufacturing of building materials is an established industry in many countries and the use of these materials is typically segmented into specific specialty trades, such as carpentry, insulation, plumbing, and roofing work.
1.3Followings are some major types of building materials.
a)Building stone

Fig:- Courses of stone
Stones are naturally occurring rocks of igneous, sedimentary or metamorphic origin. Stone or Rock structures have existed for as long as history can recall. Stone is a natural material of construction and is obtained from Quarry (open part of the natural rock from which useful material is obtains). It has been used for constructing different components of building like walls, roof, lintels etc. Stones, which are used for construction of structures, are known as building stones. Stone or Rock structures have existed for as long as history can recall. It is the longest lasting building material available, and is usually readily available. There are many types of stone throughout the world, all with differing attributes that make them better or worse for particular uses. Stone is a very dense material so it gives a lot of protection too; its main drawback as a material is its weight. Its energy density is also considered a big drawback, as stone is hard to keep warm without using large amounts of heating resources. Different forms of mortar were used to hold the stones together, cement being the most common material of mortar. Stone buildings can be seen in most major cities; some civilizations built entirely with stone such as the Egyptian pyramids.
Properties of building stone
Structure
The structure of the stone may be stratified (layered) or unstratified. Structured stones should be easily dressed and suitable for super structure. Unstratified stones are hard and difficult to dress. They are preferred for the foundation works.
Texture
Fine grained stones with homogeneous distribution look attractive and hence they are used for carving. Such stones are usually strong and durable.
Density
Denser stones are stronger. Light weight stones are weak. Hence stones with specific gravity less than 2.4 are considered unsuitable for buildings.
Appearance
A stone with uniform and attractive color is durable, if grains are compact. Marble and granite get very good appearance, when polished. Hence they are used for face works in buildings.
Hardness
It is an important property to be considered when stone is used for flooring and pavement. Coefficient of hardness is to be found by conducting test on standard specimen in Dory’s testing machine. For road works coefficient of hardness should be at least 17. For building works stones with coefficient of hardness less than 14 should not be used.
Percentage Wear
It is measured by attrition test. It is an important property to be considered in selecting aggregate for road works and railway ballast. A good stone should not show wear of more than 2%.
Porosity and Absorption
All stones have pores and hence absorb water. The reaction of water with stone causes disintegration. Absorption test is specified as percentage of water absorbed by the stone when it is immersed under water for 24 hours. For a good stone it should be as small as possible and in no case more than 5.
Weathering
Rain and wind cause loss of good appearance of stones. Hence stones with good weather resistance should be used for face works.
Toughness
The resistance to impact is called toughness. It is determined by impact test. Stones with toughness index more than 19 are preferred for road works. Toughness index 13 to 19 is considered as medium tough and stones with toughness index less than 13 are poor stones.
Resistance to Fire
Sand stones resist fire better. Argillaceous materials, though poor in strength, are good in resisting fire.
Ease in Dressing
Cost of dressing contributes to cost of stone masonry to a great extent. Dressing is easy in stones with lesser strength. Hence an engineer should look into sufficient strength rather than high strength while selecting stones for building works.
Seasoning
The stones obtained from quarry contain moisture in the pores. The strength of the stone improves if this moisture is removed before using the stone. The process of removing moisture from pores is called seasoning. The best way of seasoning is to allow it to the action of nature for 6 to 12 months.
Uses of building stone.
Millions of tones of crushed rock are needed annually for road base, paving, ready-mixed concrete and asphalt.
Sandstone which is not so hard-wearing or beautifully patterned is used for garden walls.
Although wood, straw and mud is used for houses in some parts of the world, most buildings are preferred to be built of stones.
Building wells.
Material for foundation and walling of buildings, dams, bridges, etc.
b) Bricks
Fired bricks

fig :- A pile of fired bricks.
Bricks are made in a similar way to mud-bricks except without the fibrous binder such as straw and are fired ("burned" in a brick clamp or kiln) after they have air-dried to permanently harden them .Bricks are made by molding the tampered clay to suitable shape and size which is in plastic condition, dried in sun and burnt either in kiln or clamp. It is one of the oldest and most extensively used materials of construction. Kiln fired clay bricks are a ceramic material. Fired bricks can be solid or have hollow cavities to aid in drying and make them lighter and easier to transport. The individual bricks are placed upon each other in courses using mortar. Successive courses being used to build up walls, arches, and other architectural elements. Brick require more energy to create but are easier to transport and store, and are lighter than stone blocks. Romans extensively used fired brick of a shape and type now called bricks. Building with brick gained much popularity in the mid-18th century and 19th centuries. This was due to lower costs with increases in brick manufacturing and fire-safety in the ever crowding cities. The bricks don’t require dressing and the art of laying bricks is so simple that the brickwork can be carried out with the help of unskilled labors. The common brick is one of the oldest building materials and it is extensively used at present as a leading material of construction because of its durability, strength, reliability, low cost, easy availability, etc.
A good brick earth contains the following composition:-
a )silica(50-60%) :-
It exists in clay either as free or combined. As free sand, it is mechanically mixed with clay. In combine form, it exists in chemical composition with alumina. A good brick material should contain about 50% to 60% of silica. The presence of this constituent prevents cracking, shrinking and warping of raw bricks. It thus imparts uniform shape to the bricks. The durability of bricks depends on the proper proportion of silica in brick material. The excess of silica destroys the cohesion between particles and the bricks become brittle and weak. It enables to retain its shape, imparts durability, prevent shrinkage and warping.
b) Alumina (20-30%):-
It is the chief constituent of every kind of clay. A good brick should contain 20% to 30% of alumina. This constituent imparts plasticity to the clay so that it can be molded. If alumina is present in excess, with inadequate quantity of sand, the raw bricks shrink, warp and crack during drying /burning and become too hard when burnt. It absorbs the water and render the clay plastic.
c) Lime(less than 5%):-
A small quantity of lime not exceeding 5 percent is desirable in good brick material. It should be present in a very finely powdered state because even small particles of the size of a pin-head cause flaking of the bricks. The lime prevents shrinkage of raw bricks. The sand alone is infusible. But it slightly fuses at kiln temperature in presence of lime. Such fused sand works as a hard cementing material for brick particles. The excess of lime causes the brick to melt and hence its shape is lost. The lumps of lime are converted into quick lime after burning and this quick lime slakes and expands in presence of moisture. Such an action results in splitting of bricks into pieces. It is responsible to reduce the shrinkage of brick and acts as a flux causing silica to melt. Jhama brick is the result of high percentage of lime.
D) Iron oxide (less than 7%):-
A small quantity of oxide of iron to the extent of about 5 to 6 percent is desirable in good brick material. It helps as lime to fuse sand. It also imparts red color to the bricks. The excess of oxide of iron makes the bricks dark blue or blackish. If, on the other hand, the quantity of iron oxide is comparatively less, the bricks will be yellowish in color. The presence of iron oxide in the raw materials gives the red color to the brick.
e) Magnesia:-
A small quantity of magnesia in brick material imparts yellow tint to the bricks and decreases shrinkage. However, excess of magnesia leads to the decay of bricks and affects the color and make brick yellow .It causes the clay to soften at slower rate than in most case and reduces warping.

Properties of brick:-
The following are the required properties of good bricks:
(i) Color: Color should be uniform and bright.
(ii) Shape: Bricks should have plane faces. They should have sharp and true right angled corners.
(iii) Size: Bricks should be of standard sizes as prescribed by codes.
(iv) Texture: They should possess fine, dense and uniform texture. They should not possess fissures, cavities, loose grit and unburnt lime.
(v) Soundness: When struck with hammer or with another brick, it should produce metallic sound.
(vi) Hardness: Finger scratching should not produce any impression on the brick.
(vii) Strength: Crushing strength of brick should not be less than 3.5 N/mm2. A field test for strength is that when dropped from a height of 0.9 m to 1.0 mm on a hard ground, the brick should not break into pieces.
(viii) Water Absorption: After immersing the brick in water for 24 hours, water absorption should not be more than 20 per cent by weight. For class-I works this limit is 15 per cent.
(ix) Efflorescence: Bricks should not show white patches when soaked in water for 24 hours and then allowed to dry in shade. White patches are due to the presence of sulphate of calcium, magnesium and potassium. They keep the masonry permanently in damp and wet conditions.
(x) Thermal Conductivity: Bricks should have low thermal conductivity, so that buildings built with them are cool in summer and warm in winter.
(xi) Sound Insulation: Heavier bricks are poor insulators of sound while light weight and hollow bricks provide good sound insulation.
(xii) Fire Resistance: Fire resistance of bricks is usually good. In fact bricks are used to encase steel columns to protect them from fire.
Specifications of First class brickwork
All of the bricks used should be of first class.
See the characteristics of first class bricks .
Soaking of bricks should be done by submerging in a tank before use.
Soaking should be continue until the air bubbles are ceased.
Soaking should be for a period of 12 hour before use.
Mortar specifications for first class brickwork
Material of mortar should be of standard specifications.
For mortar, cement should be fresh ordinary Portland cement of standard specifications.
Sand should be sharp and free from organic and foreign particles.
If we want to make rich mortar, sand should be coarse or medium.
For weak mortar, local fine sand may be used.
Cement sand ratio of mortar should be 1:3 to 1:6 as specified.
To get the required proportion, materials of mortar should be measured with the measuring box.
Materials of mortar should be first mixed dry to have a uniform color.
The platform should be clean for mortar mixing.
Mixing should be done at least three times.
Then water should be added gradually for workable consistency.
Mortar should be freshly mixed.
Old mortar should not be used.
Mortar should be mixed with water for one hour work so that mortar may be used before setting.
Lime Surkhi mortar
If specified lime surkhi mortar, should be mixed in 1:2 to 1:3 ratio as specified, by grinding in mortar mill for at least three hours to use on the same day.
Lime should be fresh and should be screened.
Fresh mixed mortar should be used.
For small work, hand mixing may be allowed just as in the case of cement sand mortar.
Laying of first class brickwork
Bricks should be laid in English bond unless otherwise specified.
Every course of brick should be horizontal.
Wall should be truly in plumb.
Vertical joints of consecutive brick layer should not come on each other.
Vertical joints of alternate brick layer should come directly over one another.
Closers should be of clean cut bricks.
Closers should be placed at the end of the walls but not at the other edge.
Best shaped brick should be used for face work.
Mortar joints should not exceed 6 mm or 0.5 inch in thickness.
Joints should be fully filled with mortar.
Bricks should be laid with frogs upwards except in the top brick layer.
In the top course of brickwork, frog should be laid downward.
Brickwork should be done for 1 meter or 3 feet height at a time.
When one part of the wall has to be delayed then stepping should be done at an angle of 45 degree.
Projections where made should not be more than 1/4th of the brick in one course.
All joints should be raked and faces of wall should be cleaned at the end of every day’s work.
Curing of First class brickwork
Brickwork should be kept wet for the period of at least 10 days.
Top of the walls should be flooded with water at the end of the days work by making small weak mortar edging to contain at least 2.5 cm or 1 inch deep water.
Other considerations for first class brickwork
Brickwork should be protected from the effect of sun, rain, frost etc., during the construction.
Suitable Scaffolding should be provided to facilitate the construction of brickwork.
Scaffolding should be strong enough to withstand all the expected loads to come upon them.
Measurement of First class brickwork
Brickwork should be measured in cubic meter or cubic feet.
Different kinds of brickwork with different mortar should be taken under separate item.
Thickness of wall should be taken as multiple of half brick.
For example half brick wall thickness is taken as 10 cm or 4.5 inch.
Full brick wall thickness is taken as 9 inches or 20 cm and so on.
Rate should be for the complete work including scaffolding and all tools and plants used.

Uses of bricks
Construction of walls of any size
Construction of floors
Construction of arches and cornices
Construction of brick retaining wall
Manufacture of surki (powdered bricks) to be used in lime plaster and lime concrete
c) Concrete blocks

Concrete blocks
Concrete masonry or cement – concrete masonry uses cement concrete blocks either hollow or solid for wall construction. A hollow unit is defined as that unit which has core –void area greater than 25%of the gross area. The aggregate used in the block manufacture consists of 60% of fine (sand) and 40% course aggregate of 6 to 12mm size.
The materials required for the production of the concrete blocks are aggregates, cement and water. The aggregates of various types have been used with varying degree of success and they include crushed stones, gravel, volcanic cinders, foamed slag, furnace clinker, etc. The aggregates are selected by considering the weight, texture or composition of the unit designed. The strength, texture and economy of the concrete block depend upon the careful grading of the aggregate. If locally available aggregate is suitable, it will help in achieving the economy.
The cement used is ordinary Portland cement. The water required is the normal potable water.
The hollow blocks use for the construction of wall have length 400mm,500mm,600mm etc, Similarly height of hollow blocks are 100mm,200mm and breadth are 70mm,75mm,150mm,200mm,250mm or 300mm.simply commonly used hollow block is 400mmX200mmX100mm.10mm -15mm thick mortar is used for hollow block wall construction. The compressive strength of hollow block is 1.5N/mm2 to 3 N/mm2.since the compressive strength of hollow block is low; it is not use for the construction of high load bearing wall.
Manufacturing of concrete blocks
The fully automatic plants are available for the manufacturing of high strength concrete blocks. These automatic machines produce superior quality concrete blocks. But they involve a large capital investment. The manually operated machines are also available and they can be installed at project site itself which further reduce the transportation cost of the concrete blocks from the place of production to the place of actual use.
The processes involved in the manufacturing of the concrete blocks are as follows:
Selection and proportion of Ingredients: The main criteria for the selection of the ingredients are the desired strength of the block. The greater the proportion of coarse aggregate, the greater will be the strength of the quantity of cement used.
Mixing of ingredients: The blending of aggregates, cement and water should be done very carefully. The mixing should preferably take place in a mechanical mixer. For hand mixing, extreme care should be taken to see that the cement and aggregates are first mixed thoroughly in dry state and the water is then added gradually.
Placing and vibration: The mixed concrete material is fed into the mould box upto the top level and it is ensured that the box is evenly filled. The vibration of concrete is done till it has uniformly settled in the mould box.
Curing: The block is watered after about one day of casting and it is continued for a minimum of 7 days and preferably till 28 days. The longer the curing period, the better will be the block.
Uses
It is a very common building material for the load-bearing walls of buildings, in what is termed concrete block structure (CBS) construction. Common uses for concrete block wall are interior fire-rated and air insulator partition walls. The concrete block masonry technique of construction can be adopted on a large scale of mass housing and various civil engineering projects.
d) Cement

Component materials:
Component materials required for cement making are Limestone, shale, slate, clay, chalk – Lime (60%), silica (20%), alumina (10%).
Iron oxide, magnesium oxide, sulphur trioxide, alkalies, carbon dioxide are also used as component materials in cement manufacturing.
Constituents of cement:
75% is composed of calcium silicates. Rest is made up of Al2O3, Fe2O3 and CaSO4.
Di-calcium silicate (C2S) – 2CaO.SiO2 (15-40%)
Tri-calcium silicate (C3S) – 3CaO.SiO2 (35-65%)
Tri-calcium aluminate (C3A) – 3CaO.Al2O3 (0-15%)
Tetra-calcium alumino-ferrite (C4AF) – 4CaO.Al2O3..Fe2O3 (6 -20%)
Calcium sulphate (CaSO4) – (2%)
Manufacturing process :
There are two processes for cement manufacturing.
Wet methods.
Dry methods.
In both methods raw materials are homogenized by casting, grinding and blending.
Wet process:
Mix containing homogenized constituents and 30 – 40 % of water is heated to 1510 degree Celsius in a revolving (slightly) inclined kiln. Oxides of silica, calcium and aluminum combine to form cement clinkers. Mixed with calcium sulphate (gypsum) to reduce the rate of setting and crushed into powder in ball mills before storing in silos or bags.
Dry process :
The homogenized mix is fed into the kiln and burned in a dry state. Other steps are the same as for the wet process. There is a considerable savings in fuel consumption, but workplace is dustier.

1.4 Mortars
Mortar is a bonding agent which is generally produced by mixing cementing or binding material (lime or cement) and fine aggregate (sand, surki, saw dust etc.) with water. Mortar is used to bind different building blocks like bricks stones etc. It can also add decorative pattern in brick or stone masonry. For construction purpose, different types of mortar are used. Mixes of composite mortars in common use are 1 : 1/2 : 4.5, 1 : 1 : 6, 1 : 2 : 9 and 1 : 3 : 12. Of these 4 mixes 1: 1 : 6 mix is in more common use since it has reasonably good strength and also, imparts to masonry, adequate resistance to rain penetration.

1.4.1Types of mortar
Depending upon the materials used for mortar mixture preparation, mortar could be classified as follows.
Cement Mortar
Lime Mortar
Surki Mortar
Gauged Mortar
Mud Mortar

Cement Mortar
Cement mortar is a type of mortar where cement is used as binding material and sand is used as fine aggregate. Depending upon the desired strength, the cement to the sand proportion of cement mortar varies from 1:2 to 1:6.
Lime Mortar
Lime mortar is a type of mortar where lime (fat lime or hydraulic lime) is used as binding material and sand is used as fine aggregate. The lime to the sand proportion of cement mortar is kept 1:2. The pyramids at Giza are plastered with lime mortar.
Gauged Mortar
Gauged mortar is a type of mortar where cement and lime both are used as binding material and sand is used as fine aggregate. Basically, it is a lime mortar where cement is added to gain higher strength. The process is known as gauging. The cement to the lime proportion of varies from 1:6 to 1:9. Gauged mortar is economical than cement concrete and also possess higher strength than lime mortar.
Surki Mortar
Surki mortar is a type of mortar where lime is used as binding material and surki is used as fine aggregate. Surki mortar is economic.

Mud Mortar
Mud mortar is a type of mortar where mud is used as binding material and saw dust, rice husk or cow-dung is used as fine aggregate. Mud mortar is useful where lime or cement is not available.
1.4.2 Properties of mortar
It is always desirable to use the best mortar in constructions. Therefore, the properties of a good mortar must be investigated. Generally, good mortar possesses following properties-
The main quality that mortar should possess is adhesion. Good mortar should provide good adhesion to building units (bricks, Stones etc).
Mortar should be water resistant. It should have the capability of resisting the penetration of water.
Deformability of mortar should be low.
Mortar should be cheap.
Mortar should be easily workable in the site condition.
The mobility of mortar should be good. It helps the mortar to be paved thinly and evenly.
It should possess high durability.
To improve the speed of construction, good mortar should set quickly.
Cracks should not be developed in the joint formed by mortar. It is desirable to last for long period of time without losing the appearance.
1.4.3 Importance of mortar
As a general rule, a mud mortar prepared from fine clay soil has better workability than one prepared from sandy soil and a lime mortar has a better workability than cement mortar.
Lime when used in the form of putty, gives better workability than when used in dry hydrated form. Also grinding of lime mortar in a mortar mill, results in improved workability.
A mortar made from well graded sand has better workability than one made from ungraded sand.
As a general rule, lime mortar and cement-lime mortar have good water retentivity while plain cement mortar made with coarse ungraded sand has low water retentivity.
From the view point of rain penetration, bonding property of mortar is of great importance.

1.4.4Uses of mortar
Some of the numerous uses of mortar in construction are given below.
Mortar is used to bind together the bricks or stones in brick or stone masonry.
It is used to give a soft even bed between different layers of brick or stone masonry for equal distribution of pressure over the bed.
It is used to fill up the spaces between bricks or stones for making walls tight.
It is used in concrete as a matrix.
It is used in plastering works to hide the joints and to improve appearance.
It is used for molding and ornamental purpose.
1.5 Other materials
There are different other construction materials which are explained below.
1.5.1Timber
Timber denotes wood which is suitable for building or carpentry and for various engineering and other purposes. A freshly cut surface of timber should exhibit hard and of shining appearance. A color should preferably be dark Defects. A good timber should be free from series defects such as knots, flaws, shakes etc. A good timber should be durable and capable of resisting the action of fungi, insects, chemicals, physical agencies, and mechanical agencies. The timber returns to its original shape when load causing its deformation is removed.

Seasoning of Timber
The process of removing moisture or sap from freshly cut timber is known as seasoning of timber. Seasoning of timber is the process by which moisture content in the timber is reduced to required level. By reducing moisture content, the strength, elasticity and durability properties are developed. A well-seasoned timber has 15% moisture content in it.
As fresh timber which is obtained from trees contains about 30 to 40 % sap or moisture. This sap is very harmful for the life of a timber. Therefore, it is necessary to remove that sap by applying some special methods. All those methods which are used for removing the sap from timber are collectively termed as seasoning of timber.

The following two methods are used for seasoning of timber.
Natural seasoning or Air seasoning
Natural seasoning as the name suggest is the natural way of removing moisture from timber. This method is cheep but it takes time. It requires about 60 to 90 days for soft wood.
When the timber is freshly felled or cut, it should be place at a place where air may circulate through it. But it should not be exposed to sun and wind. Time required for seasoning of timber depends on the surface exposed to the air. There should be equal dry of timber by turning the pieces frequently. Timber pieces should be kept free from the ground and other damp conditions.
Evaporation of moisture is greater from the ends than from sides. And evaporation is also greater from the upper side than lower side.the moisture quantity which is evaporated from the fresh green oak is about one third or two third of its weight. The proportion may vary according to wood type and quality and also on the nature of the soil.It has been shown by the experiments that timber looses 1/3rd of its total weight when it is kept for drying.
If we want to use timber for the purpose of carpentry, It should not be used for almost two years after it is felled. Others method may be used but for the carpenters work, natural seasoning should be the preference.
Artificial seasoning or kiln seasoning
It is the quickest method of wood seasoning and keeps the moisture contents of timber under control. The seasoning by this method generally takes four to five days under normal conditions.
Advantages of seasoned timber:
a) It has reduced weight
b) It is strong and durable
c) It has resistance to decay or rot
d) It takes high polish
e) It is easier to work
f) Its life is more.
Types of Timber Seasoning:
The main types of timber seasoning are as under.
(1)Natural Seasoning
(2)Artificial Seasoning
(a)Kiln Seasoning,
(b) Chemical Seasoning,
(c) Electric Seasoning
(3) Water Seasoning
Properties of timber
Colour : It should be uniform.
Odour : It should be pleasant when cut freshly.
Soundness: A clear ringing sound when struck indicates the timber is good.
Texture: Texture of good timber is fine and even.
Grains: In good timber grains are close.
Density: Higher the density stronger is the timber.
Hardness: Harder timbers are strong and durable.
Warping: Good timbers do not warp under changing environmental conditions.
Toughness: Timber should be capable of resisting shock loads.
Abrasion: Good timbers do not deteriorate due to wear. This property should be looked into, if timber is to be used for flooring.
Strength: Timber should have high strength in bending, shear and direct compression.
Modulus of Elasticity: Timber with higher modulus of elasticity are preferred in construction.
Fire resistance: A good timber should have high resistance to fire.
Permeability: Good timber has low water permeability.
Workability: Timber should be easily workable. It should not clog the saw.
Durability: Good timber is one which is capable of resisting the action of fungi and insects attack
Defects: Good timber is free from defects like dead knots, shakes and cracks.

Uses of timber
The versatility of timber means that it has a broad range of uses in today’s society. Timber is most commonly associated with building and construction materials, but as you will see from the list bellow, timber plays an important role in many aspects of today’s world.
Balconies, decks and terraces
Boat and Ship construction
Cladding
Fencing
Flooring
Furniture
Fuel/power generation
Glass manufacture
Musical instruments
Scaffolding
Windows

1.5.2Glass
Glass has been manufactured in New Zealand for over one hundred years, and is a common part of our daily lives. It is used commonly in windows, bottles, jars and domestic glassware, as well as as a material for artwork, such as stained glass. It is manufactured from cheap and abundant raw materials, and is readily recycled.
Many high-rise buildings now made of glass. The glass used is typically of the type not glossy, to avoid excessive glare to people who were outside the building. In addition, the glass that absorbs infrared waves are used to prevent heat from penetrating into the building. This can lead to high costs of air conditioners. In addition, the use of double-glazed windows for heat insulation outside from entering, and cool air in the building of out of buildings in hot climates or otherwise in cold climates

Properties of glass
1. It absorbs, refracts or transmits light. It can be made transparent or translucent.
2. It can take excellent polish.
3. It is an excellent electrical insulator.
4. It is strong and brittle.
5. It can be blown, drawn or pressed.
6. It is not affected by atmosphere.
7. It has excellent resistance to chemicals.
8. It is available in various beautiful colours.
9. With the advancement in technology, it is possible to make glass lighter than cork or stronger than steel.
10. Glass panes can be cleaned easily.
Some more properties of glasses are given below
Hardness and Brittleness:
It is a hard material as it has greater impact resistance against applied load. But at the same time it is brittle material as its breaks immediately when subjected to load.
Weather Resistance:
It is weather resistant as it can withstand the effect of rain, sun and wind. It can absorb, reflect and refract light as it enables us to control and manipulate natural light to influence our daily activities and frame of mind.
It has greater dimensional stability as it has low thermal expansion value. (I.e. Its change in volume with respect to temperature change as compared to other materials is very low.)
Insulation:
It is an excellent insulator against heat, electricity and electromagnetic radiation. It has a good insulating response against visible light transmission.
Certain special type of glass has high resistance against ultra-violet, infrared and x-ray transmission. It has an excellent resistance against sound transmission, provided used with proper thickness.
Chemical Resistance:
It can withstand the effect of the chemical reaction under different environment conditions or acidic effects.
It has excellent resistance to most chemicals, including solutions of inorganic alkalies and acids, such as ammonia and sulfuric acid.
Color and Shape Varieties:
It can be blown, drawn and pressed to any color, shape, and varieties.
Uses of glass
Top of Form
Bottom of Form
Glass is now being used in the building industry as insulation material, structural component, external glazing material, cladding material; it is used to make delicate looking fenestrations on facades as well as conventional windows.
1.5.3 Plastics
Plastics are said to be the most versatile materials on earth. almost all of the products we use in our daily lives contain plastics. Today, plastics materials are so widely used in the building industry that it materials are so widely used in the building industry. Many products are available which meet the various building and fire regulations.

Advantages
Plastics are strong yet lightweight, and so they are easy to transport.
They are durable, knock-and scratch resistant with excellent weather ability.
They do not rot or corrode.
They can be given any range of colors by adding pigments.
The plastics are low conductors of heat and thus are used as insulation materials in green building concepts.
The plastics products can achieve tight seals.
They can be sawn and nailed employing standard carpentry tools and skills.
They can be easily removed and recycled.
They are bad conductors of electricity.
Disadvantages and limitations
Plastics may be degraded under the action of direct sunlight which reduces their mechanical strength.
Many plastics are flammable unless treated.
High embodied energy content
Low modulus of elasticity: makes them unsuitable for load-bearing applications.
Thermoplastics are subject to creep and soften at moderate temperatures.
Thermal expansion for most plastics is high: adequate thermal movement has to be allowed in detailing.
Properties of Plastics as a Construction Material
Each plastic material has its own peculiar properties to suit its particular uses. The success of plastic as an engineering material will depends up on the selection of variety of plastic. Following are the general properties of plastic.
1. Appearance of Plastics
In the market there are so many types of models of plastics are available such as transparent, colored etc. suitable pigments are added in the process of manufacturing of plastic material to get these different properties. So, these will give good appearance to the structure and makes it attractive.
2. Chemical Resistance of Plastics
Plastics offer great resistance against chemicals and solvents. Chemical composition of plastics during manufacturing will decide the degree of chemical resistance. Most of the plastics available in the market offer great corrosion resistance. So, corrosive metals are replaced by plastic in the case of water carrying pipes, etc.
3. Durability of Plastics
Plastics with sufficient surface hardness are having good durability. Sometimes, plastics may affected by termites and rodents especially in the case of thermo-plastic types, however it is not a serious problem because of no nutrition values in plastic.

4. Electric Insulation
Plastics are good electric insulators. So they are used as linings for electric cables and for electronics tools.
5. Finishing
Any type of finishing treatment can be given to the plastics. Mass production of plastic particles with uniformity of surface finish is done by having technical control during manufacturing.
6. Fire Resistance
The resistance to temperature or fire for varieties of plastics considerably varies depending upon the structure. Plastics made of cellulose acetate are burnt slowly. PVC made plastics do not catch fire easily. Plastics made of phenol formaldehyde and urea formaldehyde are fire proof materials.
7. Weight of Plastics
The Plastics have low specific gravity generally ranges from 1.3 to 1.4. So they are light in weight and easily transportable to any place in a large quantity.
Uses of Plastics in Construction
Plastics are manufactured in different forms such as mounding pipes, sheets and films. They are formed or expanded to produce materials of low density. Dissolved in solvents or dispersed as emulsions, they are used in paints, varnishes and adhesives.
At present, plastics find use in buildings mainly in thin coverings, panels, sheets, foams, pipes etc. skilful use of plastics will expand the usefulness and life of conventional building materials and help them to function more efficiently and economically.
Uses of plastics in exterior covering, carpentry etc.
It is use in Interior Covering, Floors, Walls, Ceilings, Doors, Partitions Etc
It is use in Roof Coverings, Tightness, Domes and Lighting elements
It is use in Sanitary Equipment and Piping.

1.5.4Bitumen
Bitumen is defined as an amorphous, black or dark-colored, (solid, semi-solid, or viscous) cementations substance, composed principally of high molecular weight hydrocarbons, and soluble in carbon disulfide. It is black or brown in colour & possesses waterproofing properties. Tar and asphalt are the two varieties of bituminous materials. It is obtained by refinery processes from petroleum, and is also found as a natural deposit or as a component of naturally occurring asphalt, in which it is associated with mineral matte. Bitumen is not affected by light, air or water individually, but in combination they can make it brittle, porous and susceptible to oxidation forming blisters and crack. Bitumen should not be heated beyond 200°c.the properties of bitumen can modified by application of air, pressure or adding certain volatile material.
The main constituent is petroleum a yellowish oily substance, an excess of which makes bitumen to melt at low temperature and, asphalting hard black substance, an excess of which makes bitumen brittle and non-plastic. Its compositions are carbon 87 per cent, hydrogen 11 percent and oxygen 2 percent. Bitumen is insoluble in water and fairly resistant to most acids. Although bitumen is combustible, composite products, such as mastic asphalt, are not readily ignited. Bitumen is available in bitumen 80/100, bitumen 85/100, and bitumen 35/50, bitumen 40/50etc.

Bitumen is classified as:-
Blow bitumen:-
Blow Bitumen is obtained by passing air under pressure at a higher temperature through the bitumen. It can be used as roofing and damp-proofing felts, in the manufacture of pipe asphalts and joint filers, as heat insulating material, etc.
Cut-back bitumen –
Cut-back bitumen is obtained by fluxing asphaltic bitumen in presence of some suitable liquid distillates of coal tar or petroleum. It is mainly used in road construction and in soil stabilization (2–4%). Cut-backs are commercially manufactured in the following three groups.

1. Rapid curing (RC) cut-backs containing naphtha or gasoline.
2. Medium curing (MC) cut-backs containing kerosene.
3. Slow curing (SC) cut-backs containing light oils as fluxing agents.

Bitumen has the following five characteristic properties.
Bitumen Adheres
Bitumen is Elastic
Bitumen is Plastic
Bitumen is Viscoelastic
Bitumen Ages
Bitumen Hardens
1. Bitumen Adheres
Bitumen has excellent adhesive qualities provided the conditions are favorable. However in presence of water the adhesion does create some problems. Most of the aggregates used in road construction possess a weak negative charge on the surface. The bitumen aggregate bond is because of a weak dispersion force. Water is highly polar and hence it gets strongly attached to the aggregate displacing the bituminous coating.
2. Bitumen is Elastic
When one takes a thread of bitumen from a sample and stretches or elongates it, it has the ability to return to a length close to its original length eventually. For some bitumen this process may take longer than others. This property is referred to as the elastic character of bitumen.
3. Bitumen is Plastic
When temperatures are raised, as well as when a load is applied to bitumen, the bitumen will flow, but will not return to its original position when load is removed. This condition is referred to as plastic behavior. Applying a load means that you put a weight on the bitumen in order to subject it to stress. This could be in a lab or in the bitumen final position in the road and it is done to assess the bitumen reaction to the load.
4. Bitumen is Viscoelastic
Bitumen has a Viscoelastic character. Its behavior may be either viscous or elastic depending on the temperature or the load it is carrying. At higher temperatures there is more flow or plastic behavior, while at lower temperatures and short duration loading, the bitumen tends to be stiff and elastic. At intermediate temperatures it tends to be a combination of the two.
5. Bitumen Ages
Aging refers to changes in the properties of bitumen over time, which is caused by external condition. These changes are visible as cracks or crumbling areas. When bitumen is exposed to atmospheric conditions, the bitumen molecules react with oxygen, which results in a change of the structure and composition of the bitumen. This process of combining with oxygen, called oxidation, causes the bitumen to become brittle and hard and to change colour from dark brown or black to grey. This change is usually referred to as oxidative hardening or age hardening. This form of ageing occurs more frequently in warmer climatic or during warm seasons, causing older pavements to crack more easily. The condition can also occur where the surface films of bitumen are thin, or if there has been inadequate compaction during construction.
Uses of bitumen
Construction of road runways and platforms.
Water proofing to prevent water seepage.
Mastic floorings for factories.
Canal lining to prevent erosion.
Damp proof courses for masonry.

Model questions and their solutions

1. Very short question answer:-
Define construction material.
Ans: - Construction materials are the materials required for the different types of construction works. For example:- cement, aggregate, brick, water , concrete blocks, plastics, paints, admixture , bitumen etc.
Define building materials.
Ans: - Building materials are the materials required for the construction different types of building. For example:- cement, aggregate, brick, water , concrete blocks, plastics, paints, admixture etc.
List out the types of building materials.
Ans: - list of the building materials are given below.
Cement b) Aggregate
c) Paint d) Admixture
Glass f) Timber etc.
Define cement.
Ans: - cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Cement is one of the important construction materials Cement is often supplied as a powder, which is mixed with other materials and water.
What is mortar?
Ans :- Mortar is a workable paste used to bind building blocks such as stones, bricks, and concrete masonry units together, fill and seal the irregular gaps between them, and sometimes add decorative colors or patterns in masonry walls. In its broadest sense mortar includes pitch, asphalt, and soft mud or clay, such as used between mud bricks.
Cement mortar becomes hard when it cures, resulting in a rigid aggregate structure; however the mortar is intended to be weaker than the building blocks and the sacrificial element in the masonry, because the mortar is easier and less expensive to repair than the building blocks. Mortars are typically made from a mixture of sand, a binder, and water. The most common binder since the early 20th century is Portland cement but the ancient binder lime mortar is still used in some new construction. Lime and gypsum in the form of plaster of Paris are used particularly in the repair and repointing of buildings and structures because it is important the repair materials are similar to the original materials. The type and ratio of the repair mortar is determined by a mortar analysis. There are several types of cement mortars and additives.
List out the different types of mortar use in construction.
Ans: - list of the different types of mortar are given below.
Cement mortar b) lime mortar
c) Mud mortar d) Surkhi mortar etc
Define cutback bitumen.
Ans: - Bitumen is ‘cutback’ by adding controlled amounts of petroleum distillates such as kerosene. This is done to reduce the viscosity of the bitumen temporarily so it can penetrate pavements more effectively or to allow spraying at temperatures that are too cold for successful sprayed sealing with neat bitumen. The materials used to cutback bitumen will evaporate after application to leave the remaining material similar in hardness to the original bitumen.
What is seasoning of timber?
Ans: - Seasoning of timber is the process by which moisture content in the timber is reduced to required level. By reducing moisture content, the strength, elasticity and durability properties are developed. A well-seasoned timber has 15% moisture content in it.
List out the composition of brick?
Ans: - following are the composition of brick
a )silica(50-60%) :-
b) Alumina (20-30%):-
c) Lime(less than 5%):-
d) Iron oxide (less than 7%):-
e) Magnesia etc.
Define concrete block as building material.
Ans: - As the building’s exterior walls constructed from masonry materials, such as adobe block, concrete block, hollow concrete block etc, So the concrete block is a building material. Concrete block are generally used in hilly area for the construction of external wall to make room insulated, because hollow concrete block are used as insulator.
Define Bonds In Bricks.
Ans :- The arrangement of bricks in brick work so that the vertical joints do not come over each other is known as brick Bond.

Why Brick Bonds are Provided ?
Ans :- followings are the cause for providing brick bonds
Bonds in brick work is provided to achieve a united mass as soon as practicable* to suit the length, height and thickness of brick work and stresses to which it is subjected.
To break the continuity of vertical joints and to provide proper bond in brick masonry portion of brick ( closers or bats) are provided in alternative courses.

What do you mean by Closers?
Ans :- The portions made by cutting Brick across its length in such a manner that its one stretcher face remains uncut or half cut.
Below is the Diagram of king closer.

The above diagram is showing the Quoin** Closer.
Define brick Bats.

Ans :- The portions mad by cutting standard bricks across their width are known as brick bats.
These are named according their fraction of full length of a standard brick.

2. Short question answer:-
List out the properties of brick.
Ans: - The following are the required properties of good bricks:
(i) Color: Color should be uniform and bright.
(ii) Shape: Bricks should have plane faces. They should have sharp and true right angled corners.
(iii) Size: Bricks should be of standard sizes as prescribed by codes.
(iv) Texture: They should possess fine, dense and uniform texture. They should not possess fissures, cavities, loose grit and unburnt lime.
(v) Soundness: When struck with hammer or with another brick, it should produce metallic sound.
List out the uses of plastic and bitumen.
Ans: - uses of plastic are as given below
It is used in Interior Covering, Floors, Walls, Ceilings, Doors and Partitions
It is uses in Roof Coverings, Tightness, Domes and Lighting elements
It is uses in Sanitary Equipment and Piping.
Uses of bitumen are as listed below
Construction of road runways and platforms.
Water proofing to prevent water seepage.
Mastic floorings for factories.
Canal lining to prevent erosion.
Damp proof courses for masonry.

What are the properties of glass?
Ans: - properties of glass are listed below
1. It absorbs, refracts or transmits light. It can be made transparent or translucent.
2. It can take excellent polish.
3. It is an excellent electrical insulator.
4. It is strong and brittle.
5. It can be blown, drawn or pressed.
2. Long question answer:-
What is concrete block? Also write its steps of manufacture.
Ans: - Concrete masonry or cement – concrete masonry uses cement concrete blocks either hollow or solid for wall construction. A hollow unit is defined as that unit which has core –void area greater than 25%of the gross area. The aggregate used in the block manufacture consists of 60% of fine (sand) and 40% course aggregate of 6 to 12mm size.
The materials required for the production of the concrete blocks are aggregates, cement and water. The aggregates of various types have been used with varying degree of success and they include crushed stones, gravel, volcanic cinders, foamed slag, furnace clinker, etc. The aggregates are selected by considering the weight, texture or composition of the unit designed. The strength, texture and economy of the concrete block depend upon the careful grading of the aggregate. If locally available aggregate is suitable, it will help in achieving the economy.
The cement used is ordinary Portland cement. The water required is the normal potable water.
The hollow blocks use for the construction of wall have length 400mm,500mm,600mm etc, Similarly height of hollow blocks are 100mm,200mm and breadth are 70mm,75mm,150mm,200mm,250mm or 300mm.simply commonly used hollow block is 400mmX200mmX100mm.10mm -15mm thick mortar is used for hollow block wall construction. The compressive strength of hollow block is 1.5N/mm2 to 3 N/mm2.since the compressive strength of hollow block is low; it is not use for the construction of high load bearing wall.
The processes involved in the manufacturing of the concrete blocks are as follows:
Selection and proportion of Ingredients: The main criteria for the selection of the ingredients are the desired strength of the block. The greater the proportion of coarse aggregate, the greater will be the strength of the quantity of cement used.
Mixing of ingredients: The blending of aggregates, cement and water should be done very carefully. The mixing should preferably take place in a mechanical mixer. For hand mixing, extreme care should be taken to see that the cement and aggregates are first mixed thoroughly in dry state and the water is then added gradually.
Placing and vibration: The mixed concrete material is fed into the mould box upto the top level and it is ensured that the box is evenly filled. The vibration of concrete is done till it has uniformly settled in the mould box.
Curing: The block is watered after about one day of casting and it is continued for a minimum of 7 days and preferably till 28 days. The longer the curing period, the better will be the block.

What Timber? List out its properties.
Ans: -Timber denotes wood which is suitable for building or carpentry and for various engineering and other purposes. A freshly cut surface of timber should exhibit hard and of shining appearance. A color should preferably be dark Defects. A good timber should be free from series defects such as knots, flaws, shakes etc. A good timber should be durable and capable of resisting the action of fungi, insects, chemicals, physical agencies, and mechanical agencies. The timber returns to its original shape when load causing its deformation is removed.
Following are some important properties of timber .
Colour : It should be uniform.
Odour : It should be pleasant when cut freshly.
Soundness: A clear ringing sound when struck indicates the timber is good.
Texture: Texture of good timber is fine and even.
Grains: In good timber grains are close.
Density: Higher the density stronger is the timber.
Hardness: Harder timbers are strong and durable.

Labels: Construction materials